1. Field of the Invention
The present invention relates to a rotation control circuit and more particularly to a circuit for facilitating the positioning or maintenance of motor driven equipment by providing a jog control.
2. Background and Prior Art
Many rotating devices, such as the automatic spinwelding device disclosed in U.S. Pat. No. 3,800,400 to Mistarz require periodic or intermittent maintenance of various spinning stations. Many rotating devices, of which the above-referenced spinwelder is an example, utilize mechanical speed control in order to control the rotational speed of various work stations. Such a speed control may consist, for example, of a constant speed motor and a variable pulley drive. In connection with such equipment, it is quite difficult during maintenance or cleaning operations to accurately position the various stations by accurately causing the machine to creep or jog.
For purposes of this specification jog will be construed to be a rotational movement of a spinning device through an increment sufficient to bring a particular station or spindle into its proper position for adjustment, maintenance, cleaning or other purpose. Such discrete rotation or jog is difficult to attain in that rotating equipment will tend to rotate at line speed as long as the motor is energized. In many instances, the operator must momentarily depress a push button or the like in order to briefly energize the motor and then wait to see where the rotating equipment will stop. If the position of the equipment is not that which is required, the operator will have to repeatedly energize the motor momentarily until the required position is attained.
In addition to being inconvenient and hard on the equipment, this operation may also be considered a safety hazard in that such maintenance type of operation is generally done wthout the usual safety shields or other internal safety features of the equipment in effect.